Image sensors are used in many different types of electronic devices to capture an image. For example, consumer devices such as video cameras and digital cameras as well as numerous scientific applications use image sensors to capture an image. An image sensor is comprised of photosensitive elements that collect light that hits it and produces an electrical signal indicative of that light. Each photosensitive element is typically referred to as a picture element or pixel.
A backlit scene is a scene in which the main subject is imaged against a background that is substantially brighter than the main subject. This type of scene can cause problems for cameras in attempting to generate exposure settings for the camera. The camera typically sets the exposure in response to the bright background while underexposing the subject. This causes the main subject to turn out darker than normally desired.
Some cameras provide a backlit subject mode that enables the photographer to select whether the main subject is backlit. Such a setting requires that the photographer be knowledgeable in backlighting, recognize when it occurs, and manually select the backlit mode. Since a large number of photographers are amateurs, they either do not recognize a backlit subject situation or forget to manually set the backlighting mode. For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for detecting subject backlighting in a solid-state sensor.